Exactly this!It does whatever it needs to do to serve the story. If in the moment she needs to be visible then she is. If she needs to be heard then she is. Whatever makes the scene most interesting for the players and nudges the story forward then thats the tool in my tool box I use to serve that purpose.
Oooh!NPCs versions of powers dont necessary have to match the pcs especially when the NPC is granted power from being a part of a horrid demon amalgamation.
If you have a player being therania then i would make a minigame of it. Give all the abilities but each ability has a higher chance of drawing attention to her actions. She can project for free. Manifest visibly for 1. Speak for 1. Manipulate objects for 2. Each thing is a bonus dice on a check for zygofer to notice she is up to something. Now the player has to be careful about how much she does without having to retrrat away from her projection to hide her actions.